Tyres don't usually fail all at once, they wear down gradually, which makes it easy to miss the warning signs until you're standing at a WOF re-check wondering why you failed. Here are the 7 signs worth checking for, and what each one means for your safety and your Warrant of Fitness.
Tread Depth Near the Legal Minimum
The legal minimum tread depth in New Zealand is 1.5mm, measured within the principal grooves. Most tyres have built-in wear indicators that become flush with the tread once you've hit the limit.
Simple home check: place a 20 cent coin into the tread groove. If you can see the rim of the coin above the rubber, your tread is getting low.
Will fail WOF below 1.5mmCracks in the Sidewall
Small cracks along the sidewall, sometimes called weather checking, are usually a sign the rubber has started to age and lose flexibility, even on tyres with plenty of tread left.
Can fail WOF depending on severityBulges or Blisters
A bulge means the internal structure has been damaged, usually from a pothole or kerb strike, and the tyre can no longer hold air safely at that point. This needs attention straight away.
Automatic WOF failUneven or Patchy Wear
Wear concentrated on the inner edge, outer edge, or in patches usually points to a wheel alignment or tyre pressure issue rather than the tyre itself, worth getting checked before it happens again.
Vibration Through the Steering Wheel
Vibration at speed, especially on the motorway, can point to uneven wear, a balance issue, or in some cases a structural problem inside the tyre. Always worth ruling out.
Exposed Cords or Steel Belts
If fabric or steel cord is showing through the rubber, the tyre has worn well past a safe point and needs replacing immediately, not scheduled in for later.
Automatic WOF failThe Tyre Is Simply Old
Every tyre has a date code on the sidewall. Even with good tread, rubber compounds break down over time. Many manufacturers recommend replacement after 6 years regardless of wear.
Not Sure If Your Tyres Are Due?
Bring your car into our Onehunga workshop and we'll take a look for free, no obligation. Most checks take a couple of minutes, and if your tyres are fine, we'll tell you that too.
Call 09 622 2727Why This Matters for Your WOF
Tyres are one of the most common reasons vehicles fail a Warrant of Fitness inspection in New Zealand. Tread depth below 1.5mm, sidewall damage, and exposed cords are all automatic fail points under the NZTA's inspection requirements. Catching these signs early means you can plan for new tyres on your schedule, rather than being caught out at re-check time with your car off the road.
Frequently Asked Questions
What is the legal tread depth limit in New Zealand?
The legal minimum is 1.5mm within the principal tread grooves, measured around the whole circumference of the tyre. For better wet weather grip, it's worth replacing before you reach that limit rather than right at it.
Can I pass a WOF with slightly cracked tyres?
It depends on the severity and location of the cracking. Minor surface cracking may pass, but deeper cracks, especially near the tread or affecting the tyre's structure, will usually fail.
How do I check my tyre's age?
Look for the DOT code on the sidewall. The last four digits show the week and year of manufacture, for example "2324" means the 23rd week of 2024. If you're not sure how to read it, bring it in and we'll check for you.
Do all four tyres need to be replaced at once?
Not necessarily, but tyres on the same axle should match in size, construction and tread pattern. If you're only replacing one or two, we can advise on the best pairing.
This article is general guidance only and doesn't replace an in-person inspection. For an accurate assessment of your specific tyres, visit Auckland Tyres in Onehunga.